4 files changed, 26 insertions, 11 deletions

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c
index 0336643c2ed6..9a6434c31db2 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.c
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
@@ -665,19 +665,17 @@ iscsi_iser_session_create(struct iscsi_endpoint *ep,
 			goto free_host;
 	}
 
-	/*
-	 * FRs or FMRs can only map up to a (device) page per entry, but if the
-	 * first entry is misaligned we'll end up using using two entries
-	 * (head and tail) for a single page worth data, so we have to drop
-	 * one segment from the calculation.
-	 */
-	max_fr_sectors = ((shost->sg_tablesize - 1) * PAGE_SIZE) >> 9;
+	max_fr_sectors = (shost->sg_tablesize * PAGE_SIZE) >> 9;
 	shost->max_sectors = min(iser_max_sectors, max_fr_sectors);
 
 	iser_dbg("iser_conn %p, sg_tablesize %u, max_sectors %u\n",
 		 iser_conn, shost->sg_tablesize,
 		 shost->max_sectors);
 
+	if (shost->max_sectors < iser_max_sectors)
+		iser_warn("max_sectors was reduced from %u to %u\n",
+			  iser_max_sectors, shost->max_sectors);
+
 	if (cmds_max > max_cmds) {
 		iser_info("cmds_max changed from %u to %u\n",
 			  cmds_max, max_cmds);
diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.h b/drivers/infiniband/ulp/iser/iscsi_iser.h
index c1ae4aeae2f9..c30ceb08db21 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.h
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.h
@@ -498,6 +498,7 @@ struct ib_conn {
  * @rx_descs:         rx buffers array (cyclic buffer)
  * @num_rx_descs:     number of rx descriptors
  * @scsi_sg_tablesize: scsi host sg_tablesize
+ * @pages_per_mr:     maximum pages available for registration
  */
 struct iser_conn {
 	struct ib_conn		     ib_conn;
@@ -520,6 +521,7 @@ struct iser_conn {
 	struct iser_rx_desc	     *rx_descs;
 	u32                          num_rx_descs;
 	unsigned short               scsi_sg_tablesize;
+	unsigned short               pages_per_mr;
 	bool			     snd_w_inv;
 };
 
diff --git a/drivers/infiniband/ulp/iser/iser_initiator.c b/drivers/infiniband/ulp/iser/iser_initiator.c
index df49c4eb67f7..ca858d6bd37a 100644
--- a/drivers/infiniband/ulp/iser/iser_initiator.c
+++ b/drivers/infiniband/ulp/iser/iser_initiator.c
@@ -251,7 +251,7 @@ int iser_alloc_rx_descriptors(struct iser_conn *iser_conn,
 	iser_conn->min_posted_rx = iser_conn->qp_max_recv_dtos >> 2;
 
 	if (device->reg_ops->alloc_reg_res(ib_conn, session->scsi_cmds_max,
-					   iser_conn->scsi_sg_tablesize))
+					   iser_conn->pages_per_mr))
 		goto create_rdma_reg_res_failed;
 
 	if (iser_alloc_login_buf(iser_conn))
diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c
index 56b7240a3fc3..616d978cbf2b 100644
--- a/drivers/infiniband/ulp/iser/iser_verbs.c
+++ b/drivers/infiniband/ulp/iser/iser_verbs.c
@@ -703,19 +703,34 @@ iser_calc_scsi_params(struct iser_conn *iser_conn,
 		      unsigned int max_sectors)
 {
 	struct iser_device *device = iser_conn->ib_conn.device;
+	struct ib_device_attr *attr = &device->ib_device->attrs;
 	unsigned short sg_tablesize, sup_sg_tablesize;
+	unsigned short reserved_mr_pages;
+
+	/*
+	 * FRs without SG_GAPS or FMRs can only map up to a (device) page per
+	 * entry, but if the first entry is misaligned we'll end up using two
+	 * entries (head and tail) for a single page worth data, so one
+	 * additional entry is required.
+	 */
+	if ((attr->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS) &&
+	    (attr->device_cap_flags & IB_DEVICE_SG_GAPS_REG))
+		reserved_mr_pages = 0;
+	else
+		reserved_mr_pages = 1;
 
 	sg_tablesize = DIV_ROUND_UP(max_sectors * 512, SIZE_4K);
-	if (device->ib_device->attrs.device_cap_flags &
-			IB_DEVICE_MEM_MGT_EXTENSIONS)
+	if (attr->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS)
 		sup_sg_tablesize =
 			min_t(
 			 uint, ISCSI_ISER_MAX_SG_TABLESIZE,
-			 device->ib_device->attrs.max_fast_reg_page_list_len);
+			 attr->max_fast_reg_page_list_len - reserved_mr_pages);
 	else
 		sup_sg_tablesize = ISCSI_ISER_MAX_SG_TABLESIZE;
 
 	iser_conn->scsi_sg_tablesize = min(sg_tablesize, sup_sg_tablesize);
+	iser_conn->pages_per_mr =
+		iser_conn->scsi_sg_tablesize + reserved_mr_pages;
 }
 
 /**